Retaining rings or clips serve one major function. They furnish a shoulder or edge for holding, locking or positioning machine components such as shafts, pins and studs. Retaining clips are usually formed from thin metal sheets or wire and snapped into an angular groove or ridge on the shaft or pin to be held in place. Such clips can be used to fasten rotating or non-rotating parts or small shafts in equipment and instrument housings.
A majority of the retaining clips provided by the industry are of the one-piece or open ended variety. A frictional or snap-acting fit is used to hold the retaining clip in place. In general, the retaining clip is engaged and/or positioned about the groove of the shaft so as to force the open ends of the retaining clip apart and up and around an edge or shoulder on the ground shaft. The natural spring tendency of the displaced retaining clip is used to encompass the shaft. After installation the clip resumes its original shape (e.g., that shape prior to being imposed over the shaft).
With respect to small pins and shafts, the task of installing such a retaining ring or clip is not too difficult to perform. Sometimes a tool or jig may be used to speed the installation process. However, as shaft size increases considerable force is often necessary to place the retaining ring around and onto the shoulder of the shaft. More importantly, if one is not careful during the installation procedure, a large retaining clip, inadvertently slipping off its shaft, may act like a missile damaging equipment and injuring personnel. A considerable amount of care and time is needed if these clips are to be installed safely. In addition, if the shaft has a high thrust loading more complex retaining rings must be used.
Consequently, where large shafts are involved, or where the retaining ring hardware, as such, is large and awkward to handle or difficult to manipulate, a one-piece retaining ring of traditional design often proves to be unsatisfactory.
Other inventors have sought to improve the method in which a shaft or pin could be held in position. One method is described by A. G. Weston (U.S. Pat. No. 2,967,726). In that device, a ring is circumferentially welded to one end of a concentric pin or shaft. The ring is then joined to a fixed frame or housing by means of a threaded fastener. In such a design the pins are "custom made" and carry, as such, their own locking ring. While shaft retention is good this design precludes shaft rotation.
In a device patented by N. C. Burns (U.S. Pat. No. 1,393,943) the pins of a shackle are connected by a spring clip resting on the shoulders of each pin. A separate threaded fastener holds the clip in place. The clips do not provide any axial or thrust load support. An associated pin socket or bushing takes up the loads transmitted to the shaft. The clips merely prevent the pins from slipping out of the sockets.
Another device is illustrated by F. T. Ellis (U.S. Pat. No. 1,711,018) who uses a removable crescent shaped key to engage shoulders on a pin passing through a clevis. The key fits within a complementary housing attached to the clevis. Here the load support is good, but, due to the crescent shaped design, loading is not completely uniform around the circumference of the shaft.